1. Field of the Invention
This invention relates to a contact used for contacting an external terminal of an electric part, such as an IC package, etc.
2. Brief statement of the Prior Art
In a socket for an IC, etc., there is often a contact used having at one end thereof a terminal portion to be contacted with a circuit board, and at the other end a spring portion bent into a generally horizontal U-shape, the spring portion being provided at a free end thereof with a contacting portion on which an external terminal is to be placed for contact. The contact is plated with Au on a bed of Ni which is plated on the entire surface of the contact, a vertical elasticity being given to the contact.
The plating of Au on the bed of Ni which is plated on the entire surface of the contact is employed for the purposes of increasing the electric conductive efficiency of the contact and prohibiting the generation of oxide film on the contacting portion of the contact on which an external terminal of an IC is to be placed for contact and also on the surface of a terminal to be connected with a circuit board, etc. However, the problem that gold is very expensive is well known. Therefore, as a means for satisfying the above conditions, and saving gold for achieving a low cost, contacts have been heretofore punched out in a multiple connected state instead of being punched out individually. Ni is first plated on the entire surface of the contact in the plating process, and then Au is plated on only the contacting portion and the terminal portion with a mask applied to the remaining portion. Thereafter the contact assembly, being in the multiple connected state, is separated into individual contacts as final products.
However, although it is possible for the above-mentioned conventional method to save on the consumption of gold by plating Au only on the connecting portion and terminal portion, it has problems in that the plating process becomes very complicated. As a result, the operational expenses are increased, making it difficult to produce a low-priced contact as a component part.
Further, although it is possible for the conventional method to save on the consumption of gold, it gives rise to another problem in that an electric conductive path is formed of Ni, which has a lower electric conductivity than Au, between the contacting portion and the terminal portion. This is undesirable.
The present invention has been accomplished in order to solve the above problems inherent in the prior art.